A null test of the metric nature of the cosmic acceleration
- Centre de Physique Theorique, UMR 6207 CNRS-Luminy and Universite de Provence, Case 907, F-13288 Marseille Cedex 9 (France)
- ASI-ASDC, c/o ESRIN, Via G Galilei, I-00040 Frascati (Italy)
We discuss the testable predictions of a phenomenological model in which the accelerated expansion of the universe is the result of the action of a non-gravitational force field, rather than the effect of a negative-pressure dark energy fluid or a modification of general relativity. We show, through the equivalence principle, that in such a scenario the cosmic acceleration felt by distant standard candles like SNIa (type Ia supernovae (SNe)) depends on the mass of the host system, being larger in isolated galaxies than in rich clusters. As a consequence, the scatter in the observed SNIa Hubble diagram has mostly a physical origin in this scenario: in fact, the SNIa distance modulus is increasing, at fixed redshift, for SNe that are hosted in isolated galaxies with respect to the case of SNe hosted in rich galaxy clusters. Due to its strong dependence on the astrophysical environments of standard candles, we conclude that alternative non-gravitational mechanisms for the observed accelerated expansion of the universe can be interestingly contrasted against the standard metric interpretation of the cosmological acceleration by means of an environmental analysis of the cosmic structures in which SNIa are found. The possible absence of such environmental effects would definitely exclude the possibility of non-gravitational mechanisms being responsible for the accelerated cosmological expansion and will therefore reinforce a metric interpretation.
- OSTI ID:
- 22156806
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2008, Issue 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
Similar Records
Magnified Weak Lensing Cross Correlation Tomography
Evidence for Cosmic Acceleration Is Robust to Observed Correlations between Type Ia Supernova Luminosity and Stellar Age